/**
 * Copyright 2015-present, Facebook, Inc.
 * All rights reserved.
 *
 * This source code is licensed under the BSD-style license found in the
 * LICENSE file in the root directory of this source tree. An additional grant
 * of patent rights can be found in the PATENTS file in the same directory.
 *
 * @providesModule ReactFragment
 */

'use strict'

var ReactChildren = require('./ReactChildren')
var ReactElement = require('./ReactElement')

var emptyFunction = require('fbjs/lib/emptyFunction')
var invariant = require('fbjs/lib/invariant')
var warning = require('fbjs/lib/warning')

/**
 * We used to allow keyed objects to serve as a collection of ReactElements,
 * or nested sets. This allowed us a way to explicitly key a set or fragment of
 * components. This is now being replaced with an opaque data structure.
 * The upgrade path is to call React.addons.createFragment({ key: value }) to
 * create a keyed fragment. The resulting data structure is an array.
 */

var numericPropertyRegex = /^\d+$/

var warnedAboutNumeric = false

var ReactFragment = {
  // Wrap a keyed object in an opaque proxy that warns you if you access any
  // of its properties.
  create: function (object) {
    if (typeof object !== 'object' || !object || Array.isArray(object)) {
      process.env.NODE_ENV !== 'production'
        ? warning(
            false,
            'React.addons.createFragment only accepts a single object. Got: %s',
            object
          )
        : void 0
      return object
    }
    if (ReactElement.isValidElement(object)) {
      process.env.NODE_ENV !== 'production'
        ? warning(
            false,
            'React.addons.createFragment does not accept a ReactElement ' +
              'without a wrapper object.'
          )
        : void 0
      return object
    }

    !(object.nodeType !== 1)
      ? process.env.NODE_ENV !== 'production'
        ? invariant(
            false,
            'React.addons.createFragment(...): Encountered an invalid child; DOM ' +
              'elements are not valid children of React components.'
          )
        : invariant(false)
      : void 0

    var result = []

    for (var key in object) {
      if (process.env.NODE_ENV !== 'production') {
        if (!warnedAboutNumeric && numericPropertyRegex.test(key)) {
          process.env.NODE_ENV !== 'production'
            ? warning(
                false,
                'React.addons.createFragment(...): Child objects should have ' +
                  'non-numeric keys so ordering is preserved.'
              )
            : void 0
          warnedAboutNumeric = true
        }
      }
      ReactChildren.mapIntoWithKeyPrefixInternal(
        object[key],
        result,
        key,
        emptyFunction.thatReturnsArgument
      )
    }

    return result
  }
}

module.exports = ReactFragment
